Instantaneous frequency estimation and measurement: a quasi-local method

Abstract

This paper describes a method for estimating the instantaneous frequency and instantaneous amplitude of real signals. The method is based on engineering ideas and uses frequency separation with a filter similar to those found in radio devices. The method approximates the analytic signal, and the estimated amplitude and frequency are practically the same as those given by the analytic signal. The method is simple, fast, precise, robust to noise, easy to implement, free of parasitic cross-terms and gives results which compare very favourably with other methods for the measurement of frequency modulated signals, associated or not with amplitude modulation. Examples are given, both of mathematical signals and of real world signals (a bat echo-location signal), showing that the method can be used for precise analysis of a very large variety of signals.

Improvement of Image Reconstruction Using Multiscale Am-Fm Methods

“…the context of this paper, we will consider the cases when (single scale) to 4 (three scales), and The phase φ(x,y) of the FM function cos ψ(x,y) captures fast changing spatial variability in the image intensity. For phase function φ(x,y) we define the instantaneous frequency in terms of Δ (2) Δ is a gradient operator. There is strong interest in the development of AM-FM models due to the wide range of applicatons in various areas in signal, image and video processing.…”

Optical motion tracking in earthquake-simulation shake table testing: Preliminary results

“…We use the term AM-FM demodulation to imply the computation of the instantaneous amplitude (IA) functions a n (ξ), instantaneous phase (IP) functions ϕ n (ξ), and the instantaneous frequency (IF) vector functions ω n (ξ) = ∇ϕ n (ξ) = ∂ ∂ξ1 ϕ n (ξ), ∂ ∂ξ2 ϕ n (ξ) = ω (1) n (ξ), ω (2) n (ξ) . For the scope of this paper, the IA, IP and IF computations are carried out via the robust AM-FM demodulation algorithm proposed in [14] (see also [9] and [15] for further details).…”

Heterodyne speckle interferometer for full-field velocity profile measurements of a vibrating membrane by electronic scanning

“…The IF is given by the time derivative of the phase of a complex signal [33][34][35][36][37]. A logarithmic active CMOS image sensor array can be considered as a multidetector system connected to a DSP demodulation unit, where broadband signals, acquired from single pixels and acting as single detectors, can be analysed.…”